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biol 325 > Swimming > Flashcards

Swimming Flashcards

1
Q

How is staying in the air and in the water different

A
  1. water is denser and so there will be a buoyant force even if you don’t move
  2. in the air you need to keep flapping to maintain generate your lift through your power stroke ( needs constant movement of air over the wings)
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2
Q

How does hydrostatic pressure change with depth

A

pgh – an increase in hydrostatic pressure with depth

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3
Q

What is neutrally buoyant

A

upward force due to the mass displaced is equal to the weight of the object

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4
Q

how do we find the buoyant force

A

density of fluid* volume displaced* g

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5
Q

What happens when buoyant force > weight

A

object will float

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6
Q

what happens when the buoyant force < weight

A

object sinks but will have a lower apparent weight

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7
Q

What is the Plimsoll line

A

-indicates the height of the water that is the max for different water density

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8
Q

How do animals maintain in the water

A
  1. can expand energy to maintain position

2. can achieve neutral buoyancy (density of animal = density of water)

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9
Q

How do animals try to achieve neutral buoyance

A
  1. exchange bone for cartilage
  2. do away with shells
  3. possess fats and oil that are less dense than water
  4. use of ionic compounds ( use fewer heavy ions eg. use ammonium instead of sodium ) – this keeps osmolarity the same but decreases density
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10
Q

How can manipulating ionic salts help achieve neutral buoyancy

A
  1. salts can change water’s density by changing how water molecules stack together ( same number of water molecules take up more volume)
  2. use of lighter salt ions can reduce buoyancy
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11
Q

A Nautilis possesses a hard calcium carbonate shell, how does it offset this weight?

A
  1. the hard shell prevents compression

2. low pressure is accumulated within the chamber as fluid is pulled out, gas in the fluid comes out of solution as well

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12
Q

The Teleost fish contains a gas filled organ, how does the swim bladder increase its buoyancy

A

gas is secreted into the sim bladder, the volume of gas can alter its density

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13
Q

How do the swim bladders in surface dwelling and deeper dwelling fishes differ

A

deeper dwelling fishes have closed swim bladders - so PV= constant when pressure decreases volume increases so much the fish dies as the bladder expands. these fishes cannot make rapid vertical migrations
- surface dwelling fishes have pneumatic duct, so their swim bladders don’t change that rapidly

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14
Q

How do we determine the center of mass of an object

A

Suspend the body on a plumb line ,draw a vertical line through the body. do this twice and find where the 2 lines intersect

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15
Q

Where is the center of buoyancy of an object

A

always equal to the center of mass of an object with uniform density

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16
Q

What happens if the center of buoyancy were below the center of mass

A

the body would be unstable – the opposing buoyant and weight force may result in a rotational force that will attempt to make the object in a stable position

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17
Q

What happens of the center of buoyancy lies above the center of mass

A

the body is stable and if the object were deflected the 2 forces will produce a turning force to regain the stable condition

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18
Q

What happens if a fish were in an unstable position ( where the buoyancy force is below the center of mass)

A

The fish would have to keep exerting a force to maintain its position

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19
Q

How does the shark maintain its upwards position since its naturally stable position has the shark tipped forward

A

the tail maintains an upward directed force such that the upward and downward forces balance

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20
Q

Why do goldfishes tip over easily

A

they may have trouble controlling their swim bladder so the swim bladder expands and increases their buoyancy and inversion of the center of the buoyancy and mass

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21
Q

How can we change the momentum of water

A
  1. jetting
  2. drag based propulsion
  3. lift based propulsion
    ( flapping foils accelerate fluid)
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22
Q

What is the difference between wing function between a penguin and an eagle

A

the wings of the penguin are used to make thrust and not lift.

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23
Q

Describe lift based propulsion in a penguin

A
    • they have SYMMETRIC aerofoils
      1. the symmetric aerofoil at 0 degrees angle of attack experiences no lift only drag
      2. during the down stroke a force opposing the wing movement and thrust is produced (same for upstroke)
      3. both the up stroke and down stroke are used to generate thrust but over the course of one upstroke and downstroke the vertical forces cancel, only leaving the thrust
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24
Q

how are the tails of dolphins, whales and sharks adapted

A
  • they behave like a lift to produce hydrofoil

- the tail fins either oscillates up and down or side to side instead of rotating like a propeller

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25
Q

How can we increase thrust in the tails of dolphins

A

we can increase the downward velocity of the fin, however we would also be increasing the force resisting the movement of the fin

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26
Q

What is Kelvin’s theorem

A

the sum of the vortices should sum to zero. vorticity that sheds of the aerofoil would be of equal strength but in the opposite direction to that of the aerofoil

27
Q

Draw to vortices around a steady state foil and the wing tip vortices

A

Swimming 3 L 29 slide 3

28
Q

What kind of vortex street does a bound vortex have? Describe it

A
  • a reverse von Karman vortex street
  • wake has increased momentum
  • heaving foil increases the momentum of a fluid
  • momentum has been injected behind the wake
  • the vortex inside the wake rotates away from the aerofoil
29
Q

Describe a von Karman vortex

A
  • momentum of the fluid decreases
  • momentum has been extracted from the fluid it has flowed past the cylinder due to drag. the part of the vortex inside the wake is rotating towards the cylinder
  • stationary object in moving fluid flow: decrease in momentum
30
Q

Describe undulatory swimming ( draw a digram)

A

(L 29 slide 11).

  • a sinusoidal wave travels down the length of the body
  • the wave pushes back against the water at an angle to the direction of travel
  • the reaction force can be divided into lift and thrust. the lift ( is wasted because it gets balanced out in undulatory motion)
31
Q

Identify the dorsal fin, median fin and anal fin and caudal fin of a fish.

A

L 29 slide 15

median fin = dorsal + anal fin

32
Q

What are the 2 types of swimming propulsors

A
  1. BCF (body caudal fin propulsion) needed for body oscillations and body undulations
  2. MPF ( median paired fin) needed for fin oscillations and fin undulations
33
Q

What is the difference between body oscillations and body undulations

A
  1. undulations: body moves as a wave ( eel) - lateral displacement of the fish from head to tail is greater
  2. oscillatory: part of the body moves side to side
34
Q

Draw the difference of the envelope profile ( relative amplitude vs relative distance along body of fish) for a fish that swims relying on body undulations and another on body oscillations

A

L 29 slide 21

35
Q

compare the movement with an anguilliform (eel-like) and a thunniform ( fish like that depends on tail movement of caudal fin)

A

anguilliform: slow, large lateral movement, use of body propulsion, decreasing body stiffness, increasing turning radius, high manoeuvarability, reef/ complex habitats
thunniform: fast, small lateral movement, more body stiffness, use of tail propulsion, decreasing turning radius, decreasing manoeuvrability , found in open oceans

36
Q

How do labriform’s swim ( type of fish that is part of the median paired fin swimming that is in the oscillation section)

A

locomotion is lift-based propulsion produced by oscillations of the pectoral fin
production of thrust is the same as a flapping wing

37
Q

What is the adaptation made by the sunfish ( a MPF ; oscillatory )

A

it has evolved dorsal and anal fins of the same size.

38
Q

How do tetraodontiform sunfishes swim

A
  1. have lateral side to side acceleration
  2. there are 2 longitudinal forward acceleration peaks per complete stroke cycle – indicates that thrust is generated in both stroke directions. (longitudinal movement: movement forwards)
39
Q

How do gymnotiform’s swim ( knifefish)

A
  • have long anal fins that produce thrust, the fish produces sinusoidal waves without bending its body
  • by keeping its body straight it can detect pray (because it needs to produce a stable Electric field so it cannot move by BCF)
40
Q

Describe what manipulations can be done to the anal tail of a gymnotiform to allow hovering and swimming up

A

The gymnotiform can control the source of wave motion ( wave can travel from the front , back or both)

  • hovering is achieved when you a wave from the front and back travels slowly towards the middle
  • swimming up means that the wave from the front and back travels towards the middle quickly
41
Q

How do amiiforms swim

A

They have undulatory dorsal fins used to produce thrust

42
Q

What is the usual and atypical ways that squids travel

A

usual: lateral undulatory motion of lateral margins
atypical: jetting

43
Q

What is the formula for thrust?

A

thrust = m* delta v / t
the velocity of the fluid after it has been accelerated by the animal MINUS the velocity of the fluid moving passed the animal (= the velocity of the fluid moving past the animal)
- thrust can only occur if v_2 > v_1
- thrust equals to the rate at which momentum is added to the fluid
- the greater the momentum of fluid leabing the animal the greater the thrust

44
Q

What is the formula for the power out ( power from releasing the fluid)

A

P_out = m * v_1 * ( v_2 - v_1) / t
where v_1 is the speed of the animal
v_2 is the speed of the fluid leaving the animal

45
Q

What is the formula for the power used by the animal to produce an increase in momentum

A

P_in = m * (v_2 ^2 - v_1 ^2) / 2t

the change in kinetic energy of the swimming animal per unit time.

46
Q

How do we find the efficiency of swimming

A

P_out / P_in = 2*v_1 / ( v_1 + v_2) = n_f

Froude propulsion efficiency

47
Q

What does the Froude propulsion efficiency say

A

for the highest efficiency v_2 = v_1 however that would contradict the amount of thrust that we would be able to generate. since if we want more thrust the difference between v_2 and v_1 should be greater

48
Q

Given the paradox of Froude propulsion efficiency where we need v2 > v1 to get thrust but will never be efficient. What solution do animals have to deal with this?

A

move the largest possible mass of fluid per unit time, while giving the smallest possible increase in velocity.

49
Q

Descibe jetting in squids

A
  1. inefficient
  2. moves small amt of fluid at high velocity
  3. produces rapid movement but is highly inefficient
  4. only good for escaping predators not good for long term motion
50
Q

Describe what is the difference between lift-based propulsion and drag-based propulsion

A

Lift-based propulsion:
-fin/body encounters fluid flow at an angle <90 degrees to its surface
- forces generated are perpendicular to flow (since there is some lift force that are generated perpendicular to the relative flow)
Drag-based propulsion:
-flat surface of appendage encounters fluid perpendicular to its surface
- 2 strokes are produced with one generating more drag than the other

51
Q

Draw how undulatory oscillatory swimming looks like

A

L 29 slide 11

52
Q

What type of propulsion will a flat plate inclines at an angle experience

A

thrust based propulsion

53
Q

Why do land animals/ terrestrial animals depend on drag based swimming more

A
  1. can be sued for drag based propulsion

2. can be used for walking

54
Q

Describe drag based propulsion

A
  1. F-body and D-thrust are drag forces
  2. the drag force generated by a moving appendage moves the animal forward
  3. throughout the cycle of limb movements, drag acts on the animal’s body
  4. during the power stroke the forward force on the beetle would be 2F_thrust - F_body. hair appendages fan out during the thrust stroke to max area to generate max thrust
  5. during the return stroke, the back force on the beetle would be F_body + 2 F_feather. hairs fold against leg during recovery stroke to minimize area
    (where F_body = F_thrust - F_feather)
55
Q

How do diving birds swim under water

A

They use drag based propulsion with their feet

56
Q

What are the advantages and disadvantages of drag based propulsion

A
  • they share the same advantages and disadvantages with jetting-
    1. highly inefficient
    2. allows fast acceleration
    3. requires minimal modification of a limb: any flatish appendage can generate drag
57
Q

ow do we maximize the thrust during the power stroke an minimize the feather force during the recovery stroke in drag based prpulsion

A

max. thrust:
1. max. the surface area
2. increase the velocity of the limb through water ( v = v_oar - v1)
3. both the above will increase F_d = C_d * pV^2 *A /2
min. feather:
1. decrease the cross sectional area of the paddle
2. fold in limb close to the body during recovery
3. decrease the velocity of the limb through the water ( v = v_oar+v_1)

58
Q

What does Henry’s law state?

A
  1. the amount of gas that will dissolve into the fluid is directionally proportional to the partial pressure of the gas in contact with the fluid
59
Q

Describe where the water boatman remains. Draw the buoyancy over time of the water boatman

A

L31 slide 15. has positive buoyancy so it float. It has a bubble pressure> atmospheric pressure so air dissolves into the water. buoyancy starts to decrease as the bubble size decreases ( but still remains positively buoyant)

60
Q

Draw the buoyancy vs time graph of a water boatman

A

(L31 slide 17) remains neutrally buoyant for a long time

61
Q

How does Hb affect the bubble’s volume

A

PV=nRT so if the pressure and temperature is a constant than if we change the number of moles of molecules in the bubble we can change the volume. if Hb binds to O2 there are less moles of O2 and so the volume of the bubble shrinks. if the volume changes the buoyancy changes. in this case if vol decreases the buoyancy decreases ( less buoyant more likely to sink). By releasing or absorbing Hb, we can regulate the volume of the bubble

62
Q

What happens when the backswimmer is neutrally buoyant

A

The Hb releases O2 back into the bubble such that the volume of the bubble can be maintained. as we go deeper down the hydrostatic pressure increases such that

63
Q

Describe the full activity of a backswimmer

A
  1. air bubble replenished at the water’s surface and the Hb is fully oxygenated, the insect is positively buoyant
  2. respiration reduces O2 levels in the bubble causing it to shrink. Hb then release O2 to stabilize the bubble’s volume. this allows near -neutral buoyancy
  3. once the Hb is deoxygenated, the bubble shrinks further so the backswimmer must surface to refill the bubble and replenish O2

biol 325 (12 decks)

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